Because of the rapidly increasing utilization of in situ DNA sequence mapping to mitotic chromosomes, it is proposed that a center be established to develop and employ the most efficient techniques and to automate the procedure. Such a center would make available to laboratories involved in the cloning of DNA sequences, the capability of efficiently mapping these sequences to mammalian chromosomes. DNA sequence by in situ hybridization would therefore be made available to laboratories that do not possess technical expertise in high resolution cytogenetics essential to this mapping technique. Conditions for in situ hybridization of molecular probes to mitotic chromosomes would be further developed, focusing on improvements in probe labelling protocols. Computer sutomated processing for in situ hybridization and automated data acquisition and analysis of autoradiographic grain distributions would be developed. It is proposed that Phase I activity be centered around the development of computer programs for analysis of grain distributions on chromosomes and studies of the availability of components for microcomputer-controlled automated hybridization procedures and autoradiographic procedures. Phase I activity would also include studies of the optimization of molecular probe labelling protocols focusing particularly on the use of 35S-RNA labelling. Phase II activity would include construction of an automated in situ hybridization system using microcomputer-controlled robotics technology as well as enhancement of the computer analysis programs to provide archiving of gene sequence mapping data.